B6. Pressure from invasive species

a. Freshwater invasive species

b. Marine (coastal) invasive species

c. Terrestrial invasive species

 

Type: Pressure Indicator

 

Indicator Description

Non-native species are those that have reached Great Britain by accidental human transport, deliberate human introduction, or which arrived by natural dispersal from a non-native population in Europe.  Species that have arrived since 1500 are included within this indicator.  Most non-native species are considered benign or positive but some have a negative impact on native species through the spread of disease, competition for resources, or by direct consumption, parasitism or hybridisation; such species are termed invasive.  Invasive non-native species have one or more of these negative impacts and a high capacity to spread to natural and semi-natural habitats.  The indicator shows the change in number of invasive non-native species established across 10% or more of the land area of Great Britain, or along 10% or more of the extent of its coastline.

 

Summary

 

There are 3,163 non-native species in Great Britain, 1,980 of which are classified as established (reproducing in the wild).

This indicator contains 190 non-native species that are considered to be exerting a negative impact on native biodiversity (46 freshwater species, 36 marine species and 108 terrestrial species). The majority (184) of these species are established; six1 are long-term resident but not known to breed in the wild.

Over the period 1960 to 2017, invasive non-native species have become more prevalent in the countryside. Since 1960, the number of these species established in or along 10% or more of Great Britain’s land area or coastline has increased in the freshwater, terrestrial and marine (coastal) environments, thereby increasing the likely pressure on native biodiversity.

Comparing the latest period (2010 to 2017) with the previous one (2000 to 2009), the number of invasive non-native species established in or along 10% or more of Great Britain’s land area or coastline has remained constant in terrestrial environments (at 56 species), and has increased in both freshwater (from 12 to 13 species) and marine environments (from 23 to 28 species).

 

 

Figure B6i.  Number of non-native invasive species established in or along more than 10% of Great Britain’s land area or coastline, 1960 to 2017.

 

Figure B6i. Number of non-native invasive species established in or along more than 10% of Great Britain’s land area or coastline, 1960 to 2017.

 

Notes: The last time period covers a shorter period than the other bars (from 2010 to 2017).

Source: Botanical Society of Britain & Ireland, British Trust for Ornithology, Centre for Ecology & Hydrology, Marine Biological Association, National Biodiversity Network.

 

Assessment of change in the number of invasive non-native species established in or along 10% or more of Great Britain’s land area or coastline

 

Long term

Short term

Latest year

Freshwater invasive species

indicator declining
1960–2017

Not assessed

Not assessed

Marine (coastal) invasive species

indicator declining
1960–2017

Not assessed

Not assessed

Terrestrial invasive species

indicator declining
1960–2017

Not assessed

Not assessed

 

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Last updated: July 2018

Latest data available: 2017

 

1The six long-term residents species included the indicator are two species of terrapin (Emys orbicularis, Trachemys scripta) and four freshwater fish (Ameiurus melas, Leuciscus idus, Salvelinus fontinalis, Oncorhynchus gorbuschas).